Process of copper brazing



I NOV. 17, 1936. R TERRY 2,060,959

PROCESS OF COPPER BRAZING Filed Oct. 29, 1954 gwumrm 1 2305M? 72h? Patented Nov. 11, 1936 PATENT OFFICE PROCESS OF COPPER BRAZING Robert Terry, Detroit, Mich, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application October 29, 1934, Serial No. 750,517

4 Claims. (01. 113-112) This invention relates to copper brazing. The use of copper brazing to secure close fitting metal parts together is quite generally used throughout manufacturing methods. 5 method of accomplishing this is to place the cleaned parts in juxtaposition and then to melt a portion of copper and allow it to flow into the opening between the two parts and fill the same, adhering to the sides of the parts. In order to accomplish this satisfactorily, the spacing between the two parts is very small. If the distance between them is large or is irregular, it has been found that this method will not give a satisfactory bond.

- It is the object of this invention to provide a method of satisfactorily copper brazing two metals together where the fitvbetween the two is irregular or too wide to support the molten copper alone therein until it hardens. It is a further object of this invention to provide a method of copper brazing in which the molten copper is drawn into and held in the joint until solidification occurs. v

,For a better understanding of the nature and objects of this invention, reference is made to the following specification, wherein there are described the embodiments of my invention which are illustrated in the accompanying drawing.

Figure 1 is a perspective view showing two parts so that it is desired to braze.

a In Figure 1' is shown a part to to. which it is desired to secure a tip [2 similar to'the application of a cutting point on a turning cutter for a lathe. As is clearly shown in the drawing, the two surfaces do not fit'closely, the space ll be- 40 tween the two being, of course, exaggerated.

' A paste it as shown in Figure 2 is pressed into this opening with a spatula or similar device until the opening is filled. 'lhis paste is composed of reduced iron powder and clear lacquer I or any other suitable vehicle which are mixed together to form a, suitable plastic mass which will not flow but is similar to ordinary paste in constitution.

when the opening has been filled with this 50 paste, a piece of copper, indicated at I8, is placed adjacent the-edge ofthe crack and the whole is heated. During heating, the lacquer between the particles of iron decomposes and gas is driven oil,

The usual creating voids between the particles of iron so that the paste is transformed to the character of a sponge. As the copper melts, the molten copper is sucked in by the sponge action completely filling the crack and being held there by the iron 5 particles until solidification takes place.

In Figure 3 is shown a microscopic view of the joint, the particles of iron 10 are shown which have not changed their form, and the spaces between them are filled now with copper 22 in- 10 stead of lacquer. The use of lacquer as a binder has proven very satisfactory, since it decomposes, leaving very little residue before the copper flows in.

It will therefore be seen that the action of the 15 paste is two-fold in that it absorbs the copper into the opening by a sponge action and supports the copper therein until it is hard.

I claim:

1. A method of copper brazing two metals tom gether comprising packing the space between the two with a paste of a vehicle and particles, placing a piece of copper adjacent the space, applying heat to decompose the vehicle first and later cause the molten copper to be soaked into the voids left a by the vehicle, the mass being held by the particles until solidification.

2. A method of copper brazing two metals together comprising packing the space between the two with a paste, applying heat which causes an voids therein while the remainder still retains sufilcient structure to support the whole mixture, then sucking intothe voids a binding material to provide a tight joint upon solidification.

3. A method of copper brazing two metals toas gether comprising filling the space between the two with a paste having a vehicle and particles therein in which upon an application of heat the vehicle decomposes and leaves voids, applying a sealing material adjacent the space, heating the 40 whole which draws the material into the voids, the particles maintaining the structure in the space between the metals until the sealing material has solidified.

4. A method of copper brazing two metals together comprising packing the space between the two parts with a paste composed of iron particles and lacquer, placing adjacent the space a piece of copper and applying heat whereby the lacquer first decomposes leaving voids that'suck in the so copper upon its melting and the iron particles hold it in place until it solidifies.

. ROBERT TERRY. 

